Field of Invention
The invention relates to an optical system and, in particular, to a light source system.
Related Art
A conventional light source system can include a single light source or a plurality of light sources. The light source system including a plurality of light sources can provide higher illumination and can be applied to an autostereoscopic 3D projection apparatus, so that it becomes the mainstream.
However, different from the light source system including a single light source, the light sources in the light source system including a plurality of light sources need to be coupled in the situation of not increasing the etendue and the light loss.
One solution is to use a laser source as the light source and the etendue can be decreased since the laser source has less etendue than an ultrahigh performance (UHP) lamp. Besides, another advantage of using laser source is that the size of the laser source is smaller, so the increment of the total size of the light source system can be limited even if a plurality of laser sources are used.
The second solution has two methods for the light coupling. One method is to use optical fibers to couple the plurality of light sources and guide the light to a specific direction, but the total light loss will be increased with the increased length of the optical fibers. The other method is to use a stepped reflector/reflective prism to guide the light of the plurality of light sources disposed it an array to a specific direction. However, due to the interval between the adjacent reflectors and the divergence caused during the light travelling, the etendue will be unavoidably accumulated by the multiple effect of the stepped reflector.
Therefore, it is an important subject to provide a light source system that has lower etendue and less light loss and can couple a plurality of light sources.